Environmental factors, combined with genetic susceptibility, rather than genetics alone, are now considered key in understanding the etiology of autism spectrum disorders (ASD). The lack of methods to determine environmental exposures during critical periods of development has been the bane of ASD studies investigating gene/environment interactions. The investigators have previously established that semi-volatile organic chemicals, including pesticides, analgesics, and phthalates, and/or their metabolites, are stored in exfoliated deciduous teeth at measurable levels in typically-developing children. This novel technique allows detection and quantification of exposures, and provides a timeline for exposure based on when teeth were formed. The project uses a case-control approach to examine exposures. Families are recruited through an established network of community partners and online autism organizations. The hypothesis is that compounds stored in deciduous teeth can be evaluated as biomarkers for prenatal and perinatal exposures in autism case-control studies. Replication of recent identification of these biomarkers in teeth (as proposed in aim 1) will be, in itself, an extremely valuable contribution to exposure science. The specific aims are to: 1) identify semi-volatile organic compounds present in exfoliated deciduous teeth that can be evaluated as biomarkers for exposures; and 2) assess whether these stored chemicals in teeth are differentially distributed between ASD and typically developed children. Even if it is not true that cases are differentially exposed, it may be that specific genetic susceptibilities to the exposures identified could explain ASD risk. The data collected in this study is essential for future studies exploring the role of genetic susceptibility. Ultimately, this research may provide evidence and guidance for avoiding certain pre- and post-natal exposures to decrease the risk for autism or offer therapeutic targets. This Trailblazer study is expected to be the precursor to a series of investigations which will focus on specific individual genetic susceptibilities to the compounds identified in deciduous teeth in determining the risk for ASD.